Something that I don't understand is how safe a BHSE would be without the limiting resistors. I read a few days back that at the voltage swings the amp is capable of, you could reach harmful levels. What happens to these cans that require double the bias / voltage swing than stax pro-bias cans?

Are you concern about the bias voltage or the swinging voltage on the stators? Normally we would definitely put some current limiting resistors in series with the bias voltage. This not only helps prevent over current in case something should go wrong, but it also helps keep the diaphragm constantly charge. It doesn't matter how high your bias voltage is, these resistors are a must have.

As for the swinging voltage to the stators, that is something you must be very careful. There is no current limiting circuit in between - well, unless you're using come special design current limiting amplifier. Your only option is to make sure that your stators and cable are very well insulated.

People buy SUVs and sports cars for different reasons. For instance hauling around a bunch of equipment (or kids) versus performance driving, looking rugged versus looking well off, etc. etc.

Now I could see the above comparison being more fitting for traditional full sized headphones versus in-ear monitors, since both target rather different needs and have very distinct functional considerations, but I really don't feel the differences between electrostats and orthos are drastic enough to merit the same division. People use both types of transducers for listening to music at home primarily, and in both cases you're pretty much tied to your setup.

I get that both orthos and stats have their unique characteristics and respective sonic traits, but the differences aren't so vast that it becomes counterproductive to compare the two categories in my mind. Actually, it seems to me like there's more variation within each group than between them often times. Put another way: in my experience there are "sports cars" in both categories. Headphones like the Abyss, SR-009, Floats, and TakeT all have their respective strengths and weaknesses, and that's *why* comparisons are helpful in the first place. It doesn't have to turn into a pissing match, either.

Also yes, you have to take the amp into consideration when it comes to comparing electrostatic headphones and dynamics---be they electro or ortho---but both groups have sufficiently high-end offerings to drive them. I don't see why that makes comparing them off limits. It's another practical consideration to note.

Something that I don't understand is how safe a BHSE would be without the limiting resistors. I read a few days back that at the voltage swings the amp is capable of, you could reach harmful levels. What happens to these cans that require double the bias / voltage swing than stax pro-bias cans?

The output resistors are a relatively new addition and indeed first seen in the T2. Without them the amps are perfectly safe as you are very unlikely to ever see the full output swing of these amps. The headphones will have given up the ghost well before that time.

I would recommend output resistors on the QA too but the exact value would have to be calculated.

The two new upcoming amps: one with built-in amplifier (no preamp) and one with built-in integrated amp (preamp with volume control) are said to be priced around 2100 and 3300 euros, respectively. These prices exclude VAT by the way, so the actual price will be higher in Germany and other countries where VAT is added. They use the same chassis as the current power supply box, so the size will remain the same but they will weigh a bit more. They will be released in a few weeks.

As I've said before, it is recommended that one use an amp that can output 30-60 watts per channel to get the best out of the Float QA with its transformer box. The upcoming built-in amp and integrated amp that will output 60 watts per channel, which is supposedly enough to drive the Float QA to its fullest.

Although I've considered buying the upcoming amps, I'm still thinking of purchasing a dedicated integrated amp for possibly better results with the Float QA. YMMV.

The two new upcoming amps: one with built-in amplifier (no preamp) and one with built-in integrated amp (preamp with volume control) are said to be priced around 2100 and 3300 euros, respectively. These prices exclude VAT by the way, so the actual price will be higher in Germany and other countries where VAT is added. They use the same chassis as the current power supply box, so the size will remain the same but they will weigh a bit more. They will be released in a few weeks.

As I've said before, it is recommended that one use an amp that can output 30-60 watts per channel to get the best out of the Float QA with its transformer box. The upcoming built-in amp and integrated amp that will output 60 watts per channel, which is supposedly enough to drive the Float QA to its fullest.

Although I've considered buying the upcoming amps, I'm still thinking of purchasing a dedicated integrated amp for possibly better results with the Float QA. YMMV.

People buy SUVs and sports cars for different reasons. For instance hauling around a bunch of equipment (or kids) versus performance driving, looking rugged versus looking well off, etc. etc.

Now I could see the above comparison being more fitting for traditional full sized headphones versus in-ear monitors, since both target rather different needs and have very distinct functional considerations, but I really don't feel the differences between electrostats and orthos are drastic enough to merit the same division. People use both types of transducers for listening to music at home primarily, and in both cases you're pretty much tied to your setup.

I get that both orthos and stats have their unique characteristics and respective sonic traits, but the differences aren't so vast that it becomes counterproductive to compare the two categories in my mind. Actually, it seems to me like there's more variation within each group than between them often times. Put another way: in my experience there are "sports cars" in both categories. Headphones like the Abyss, SR-009, Floats, and TakeT all have their respective strengths and weaknesses, and that's *why* comparisons are helpful in the first place. It doesn't have to turn into a pissing match, either.

Also yes, you have to take the amp into consideration when it comes to comparing electrostatic headphones and dynamics---be they electro or ortho---but both groups have sufficiently high-end offerings to drive them. I don't see why that makes comparing them off limits. It's another practical consideration to note.

You're right, I could have found a better fitting analogy

The thing is, to these ears, stats sound like stats. Of course they're all very different but they all share a certain family trait that one cannot ignore. When I'm listening to them, I cannot forget that they're electrostatic. To me they're a completely different listening experience and therefore they cannot be compared objectively to a representative of another technology which offers a different experience. To me it's just a matter of preference and as such it cannot be objectively put into words, especially since language is such an awful tool to describe sensitive experiences. That's one of the reasons why I don't write reviews. I'm not saying that reviews are not helpful though, in many cases they are but I just don't know how to properly write one without going all the way to 6moons-like woowoo....

That said, I tend to see every piece of Hi-fi equipment as different rather than better/worse so I'm guess that I'm flawed.

The output resistors are a relatively new addition and indeed first seen in the T2. Without them the amps are perfectly safe as you are very unlikely to ever see the full output swing of these amps. The headphones will have given up the ghost well before that time.

I would recommend output resistors on the QA too but the exact value would have to be calculated.

I am sorry but I really have to disagree with the above.

All of the above are assumptions at best. Please take some really well made recording of symphonic orchestra ( anything from Ken Kreisel ( of Miller & Kreisel direct to disc fame ), prof. Johnson, 2L, etc, etc should do ) and attach an oscilloscope to the output of either your source, preamp or final amp.

If you do not find the tympani ( usually at the finale of a composition ) the loudest peak, or an ocassional outburst from some soprano on steroids, I am the greatest ballet dancer of all time - and I am most definitively not.

You have to use a dedicated probe for testing electrostatic amps - voltage swing is beyond spec for normal probes. Commercial ones tend to be extremely bulky ( for a reason, they want user to be safe when handling say 10 KV for which these probes are usually made ) , but are meant more for DC than AC measurements - they are usually uncapable of measuring frequency response as high as required. DIY is usually the only way, but you MUST know extremely well what you are doing.

Now assume you have your probe to check for output voltage levels while the music is playing. You should find the source and preamp should be free of any trouble - in stark contrast to the final amp, be it normal low voltage low impedance amp for speakers/headphones most commonly used in audio

or its electrostatic counterpart. You can perfectly well land at the volume setting that will clip at the loudest peaks in the bass if the volume is adjusted by ear - with peaks and the resulting distortion/compression being short in duration enough not to be directly objectionable. Yet the oscilloscope will clearly show clipping. Lower the level just below the clipping is observed - and it will most likely be too low in perceived volume, as it can be anything from 2 to 6 dB difference in level, depending on amp, programme material and listener sensibility/tolerance. 2 dB is audible, 6 dB is most definitely too quiet. ESL's Aichille's heel will forever remain the ultimate loudness achievable, particularly in the bass.

As noted in one of my previous posts, Stax knows as much as anybody regarding electrostatics. I have never seen T2 or its schematics, but I assume they made everything possible WITHIN the limits of safety. Those stator output limiting resistors can not be there for any other reason than to protect the listener's bare life should all the insulation fail. Frankly, well performing ESL amp, particularly headphone ESL amp, and safety unfortunately do not go hand in hand. It is dabbling in grey area, for example, Jecklin Float brochure of the past mentioned only bias voltage and its minuscule current as being absolutely safe, which is true - but what about stator outputs, connected through a transformer to XY W powerful amplifier? Just to put things into perspective regarding the first generation of Floats - VU meters on Phase Linear amp barely moved when music was playing on Magnaplanar Tympani 1D speakers, which are anything but known for their efficiency - yet REALLY came to life when the same selection of music was being played over the Jecklin Floats connected to the same amp for the same perceived level as on speakers.

There is a reason EU prohibited big direct electrostatic amps - like the ones in Acoustat and Beveridge (past) top offerings. I do not know the exact voltage/current limits over which this directive steps into action - but you can bet some of the headphone amps on the market are there about, if nor already exceeding it.

I did build as non compromised set of ESL amp and earspeakers as I possibly could - back in 1986 or so. It dwarfs anything seen up to this day.

I decided never to make it commercially available , well before EU banned such amps. It doubles, very nicely, as ELECRostatICCHAIR.

More than capable of giving the listener the ULTIMATE transient ...at least on this world.

Remarks from the member wachara clearly point to the fact that he has done considerable work on electrostatics and speaks from the experience gained first hand and not interpreting some manufacturer's comments.

Stax, as any quality prudent manufacturer, is saying less than they know. Just remember the level of information given during Sennheiser's Axel Grell's "interview" where head-fi members and other enthusiasts could post questions for him online - he revealed essentially zero beyond what was already known regarding Sennheiser before.

P.S: Forgot to state the obvious: no commercial electrostatic headphone (should be )/is available that can not handle the full output from its dedicated high voltage amp - including infinite time amount of DC and/or permanent clipping. Damage occurs only when excessive voltage is present on the transducer itself. In that sense, properly designed ESL amp/phone combo is the most electrically robust transducer you can possibly think of. However, it IS possible to overvoltage and damage/destroy ESLs through transformer coupling when using too heavy input - it can be as brisk as tick or pop from an LP.

For this reason, Sennheiser did use heavy duty back to back connected zener diodes on the input to the transformer (or output of the conventional speaker amp) in their Unipolar 2000/2002 transformer box. Now - if you lust just to hear how a truly hard clipping sounds, look no further. The amp should be capable of driving (near) short circuit and/or be protected from blowing up under these conditions. Removing those diodes to improve sound will see off fragile electret drivers in a matter of seconds/minutes/days . Just settle for the SPLs achievable with diodes in place - there is a great thread on Unipolar going on head-fi, they are kind of electrostatic ( electret ) sleepers.